The present invention relates to a method of manufacturing a magnetic sensor comprising at least two magnetoresistive elements arranged one on the other. Such a magnetic sensor is used for detecting a magnetization pattern recorded on an encoder such as linear encoder and rotary encoder or for reading out information recorded on a magnetic record medium such as magnetic tape and magnetic disc.
In Japanese Patent Application Publication Nos. 37,204/78 and 37,205/78, there has been disclosed a known magnetic sensor comprising two magnetoresistive elements (hereinafter abbreviated as MR element) arranged on respective side of an insulating film and magnetically biased with each other. In such a known magnetic sensor, a first electroresistive film (hereinafter abbreviated as MR film) is applied on an insulating substrate, then an insulating film is applied on the first MR film and finally a second MR film is applied on the insulating film. In such a construction, in order to obtain a stable detection output, the first and second MR elements should have identical magnetic properties with each other. In the known method of manufacturing the magnetic sensor, after the first MR film and a first electrode film have been deposited on the insulating substrate successively, these films are etched in accordance with a given pattern. Then after the insulating film, the second MR film and a second electrode film have been deposited, these films are subjected to an given patterning treatment. However, such a known manufacturing method requires several deposition and photoetching processes, and thus, there is a drawback that the manufacturing process becomes complicated. Further, since the first and second MR films are formed into the given patterns by means of separate etching steps, the accuracy of dimension and shape could not be maintained, so that the magnetic properties of the MR elements become different from each other. Moreover, in case of forming electrical connections to the first and second MR elements, there might be easily produced undesired short-circuits.